Evaluation of β3-adrenoceptor-mediated relaxation in intact and endotoxin-treated equine digital veins

Mallem, Yassine; Gogny, Marc; Gautier, Freddy; Bucas, Véronique; Desfontis, Jean‐Claude

doi:10.2460/ajvr.2003.64.708

Cited by 20 publications

(19 citation statements)

References 39 publications

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“…coronary arteries and cerebral arteries) (Brawley et al, 2000). Recently, several in vivo and in vitro studies have demonstrated the functional expression of b 3 -AR in some vascular tissues (Gauthier et al, 2000;Mallem et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Adrenergic regulation of vascular smooth muscle tone in calf digital artery

Belloli¹,

Badino²,

Arioli³

et al. 2004

Vet Pharm & Therapeutics

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Radioligand binding studies and functional assays on isolated smooth muscle preparations were performed in order to obtain a biochemical and functional characterization of the beta-adrenoceptor (beta-AR) subtypes involved in regulation of the smooth muscle relaxation of the calf's common digital artery. The results indicate that the common digital artery possesses two beta-AR populations (40% beta(1) and 60% beta(2)) and the beta(2)-subtype appears to predominate as far as function is concerned. Only the beta(2)-AR agonists clenbuterol and fenoterol caused dose-related relaxant effects, antagonized by propranolol, when tested in preparations precontracted both with PGF(2alpha) (1.4 x 10(-5) m) and noradrenaline (1.2 x 10(-6) m). In noradrenaline precontracted preparations the beta(1)-AR selective agonists dobutamine and xamoterol caused vasodilation which was not antagonized by (+/-)propranolol. While the functional relaxant effects of dobutamine may be attributed to its potent competitive alpha-AR blocking activity, further investigations are required to explain the effect of xamoterol. The vasodilator effect of (+/-)isoproterenol was irregular. The recorded contractile effects, mainly at dosages greater than 10(-6) m, suggest the loss of drug selectivity for beta-AR and alpha-AR activation. Indirect evidence indicates that the alpha-adrenoceptor (alpha-AR) population in this tissue which produces a strong contraction is functionally dominant over the beta-AR, suggesting limited therapeutic benefit for beta-AR drugs to control blood flow disorders in the calf's distal limb.

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Section: Introductionmentioning

confidence: 99%

Adrenergic regulation of vascular smooth muscle tone in calf digital artery

Belloli¹,

Badino²,

Arioli³

et al. 2004

Vet Pharm & Therapeutics

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Section: Discussionmentioning

confidence: 99%

“…The antioxidant effect demonstrated in this study could be relevant in the prevention of these pathologies where ROS are implicated. Recently, some authors have shown that ROS were implicated in the endotoxin-induced impairment of b-adrenoceptor-mediated vasodilation in equine digital veins (Mallem et al, 2003(Mallem et al, , 2006. In agreement with these authors, our results suggest a synergistic effect of vasodilator and antioxidant properties of ACP that could be beneficial for the treatment of laminitis in horses.…”

Section: Discussionmentioning

confidence: 99%

In vivoadministration of acepromazine or promethazine to horse decreases the reactive oxygen species production response of subsequently isolated neutrophils to stimulation with phorbol myristate acetate

Peters

Franck

Pequito

et al. 2009

Vet Pharm & Therapeutics

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The previous experiments have shown that some phenothiazines have antioxidant and anti-inflammatory properties in vitro. In this study the inhibition of the production of reactive oxygen species (ROS) by neutrophils was studied in two groups of horses, which received a dose of 0.1 mg/kg of either acepromazine or promethazine intravenously. Blood samples were collected before (T0) and 0.5, 1, 3 and 5 h after drug administration. The chemiluminescence (CML) response of neutrophils was measured ex vivo in the presence of luminol for a period of 10 min and the maximum CML value (peak value) recorded. There was a significant inhibition of the ROS production in the acepromazine treated group (49% inhibition) at 5 h after administration and in the promethazine group (24% inhibition) at 3 h after administration (P < 0.05 vs. T0). These findings are of therapeutic relevance in the use of phenothiazines in equine patients with inflammatory diseases where neutrophil activation and ROS production are implicated.

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“…In our laboratory, we currently carry out experiments on b-adrenoceptor activation, which mediates a concentrationdependent relaxation in rat, guinea-pig and equine isolated blood vessels. [6][7][8][9] To illustrate the use of nlme models, we chose the data obtained in a study of b-adrenoceptor-mediated effects in rat isolated thoracic aorta rings. [9] The experiments were performed in 12-week-old male Wistar Kyoto (WKY) rats.…”

Section: Experimental Designmentioning

confidence: 99%